System and method for obtaining bodily function measurements using a mobile device

ABSTRACT

Methods, systems, computer-readable media, and apparatuses for obtaining at least one bodily function measurement are presented. A mobile device includes an outer body sized to be portable for user, a processor contained within the outer body, and a plurality of sensors physically coupled to the outer body. The sensors are configured to obtain a first measurement indicative of blood volume and a second measurement indicative of heart electrical activity in response to a user action. A blood pressure measurement is determined based on the first measurement and the second measurement. The sensors also include electrodes where a portion of a user&#39;s body positioned between the electrodes completes a circuit and a measurement to provide at least one measure of impedance associated with the user&#39;s body. A hydration level measurement is determined based on the measure of impedance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/137,425, filed Sep. 20, 2018, entitled “SYSTEM AND METHOD FOROBTAINING BODILY FUNCTION MEASUREMENTS USING A MOBILE DEVICE,” which isa continuation of U.S. application Ser. No. 14/278,062, filed May 15,2014, entitled “SYSTEM AND METHOD FOR OBTAINING BODILY FUNCTIONMEASUREMENTS USING A MOBILE DEVICE,” which claims priority to and thebenefit of U.S. Provisional Application No. 61/895,995, filed Oct. 25,2013, entitled “SYSTEM AND METHOD FOR OBTAINING BODILY FUNCTIONMEASUREMENTS USING A MOBILE DEVICE,” all of which are incorporatedherein by reference in their entirety and for all purposes.

BACKGROUND

Aspects of the disclosure relate to mobile devices, and moreparticularly, a system and method for obtaining at least one bodilyfunction measurement of a user operating a mobile device.

It is often desirable for a user to be aware his/her bodily functionmeasurements, which may provide physiological measures of stress,measures of hydration, and other measures of general health.Physiological measures of stress may be used to communicate to a userinstructions to alter his/her behavior, e.g., taking a break, takingdeep breaths, etc. Measures of hydration may be used by athletes orgenerally active individuals to ensure that they stay hydrated tomaintain physical performance. Additionally, this information may beuseful for individuals who work in hot or dry environments and mustmaintain proper hydration. Further, this information may be useful forelderly individuals whose sense of hydration is decreased and are moreprone to becoming dehydrated. Thus, important bodily functionmeasurements may include measurements of a user's blood pressure and/orhydration state.

A user's blood pressure may be measured using a pulse-measuring device.Typical pulse-measuring devices use either photoplethysmography (PPG) orelectrocardiography (ECG) to measure a user's pulse. A user's systolicblood pressure or diastolic blood pressure may be determined using acombination of the PPG and ECG using a technique known as pulse transittime (PTT). The systolic blood pressure, along with other inputs such aspulse rate variability (PRV) and galvanic skin response (GSR) may beuseful in determining the user's physiological measures of stress.However, existing mobile device solutions for obtaining PPG measurementsand ECG measurements can only obtain measurements for one or the other.That is, existing mobile device solutions can only obtain a PPGmeasurement or an ECG measurement, but not both.

A user's hydration state may be determined by measuring a total bodywater amount using a bioelectric impedance analysis (BIA). BIAmeasurements are typically accurate and may fall within 200 ml of theactual value when performed properly. Typically, existing solutions tomeasure BIA require professional equipment in a clinical setting.Additionally, the few devices that exist to measure BIA outside of aclinical setting are not very mobile, e.g., they may not fit within auser's pocket or be integrated into another device that the usertypically always has with them.

Accordingly, a need exists for a mobile solution to obtain both PPG andECG measurements used for determining a user's blood pressure and toobtain a body water content measurement used for determining a user'shydration state.

BRIEF SUMMARY

Certain embodiments are described that for obtaining at least one bodilyfunction measurement of a user operating a mobile device.

In some embodiments, a mobile device for obtaining at least one bodilyfunction measurement comprises an outer body sized to be portable for auser, a processor contained within the outer body, and a plurality ofsensors physically coupled to the outer body for obtaining dataaccessible by the processor. One or more sensors of the sensors isconfigured to obtain a first measurement indicative of blood volume inresponse to a user action. One or more of the sensors is configured toobtain a second measurement indicative of heart electrical activity inresponse to the user action. The processor is configured to facilitategeneration of a blood pressure measurement based on the firstmeasurement and the second measurement.

In some embodiments, the mobile device is configured to perform aprimary function and a secondary function, and wherein the processor isconfigured to facilitate generation of the blood pressure measurement asthe secondary function of the mobile device.

In some embodiments, the first measurement indicative of blood volumecomprises a photoplethysmography (PPG) measurement.

In some embodiments, the second measurement indicative of heartelectrical activity comprises an electrocardiography (ECG) measurement.

In some embodiments, the one or more of the sensors configured to obtainthe first measurement comprises at least one light sensor, and whereinthe mobile device further comprises at least one light source and the atleast one light sensor measures reflected light from the light sourcereflected off of blood vessels within a user of the mobile device toobtain the first measurement.

In some embodiments, the one or more of the sensors configured to obtainthe second measurement indicative of blood volume comprises at least afirst electrode and a second electrode, and wherein a portion of a userof the mobile device's body completes a circuit between the firstelectrode and the second electrode.

In some embodiments, the mobile device is a watch.

In some embodiments, the mobile device is a smartphone device.

In some embodiments, method for obtaining at least one bodily functionmeasurement via a mobile device comprises obtaining, via a plurality ofsensors physically coupled to an outer body of the mobile device, afirst measurement indicative of blood volume in response to a useraction. The method further comprises obtaining, via the plurality ofsensors, a second measurement indicative of heart electrical activity inresponse to the user action. The method also comprises facilitating, viaa processor of the mobile device, generation of a blood pressuremeasurement based on the first measurement and the second measurement,wherein the processor is contained within the outer body of the mobiledevice, the outer body sized to be portable for the user.

In some embodiments, an apparatus for obtaining at least one bodilyfunction measurement comprises means for obtaining, via a plurality ofsensors physically coupled to an outer body of a mobile device, a firstmeasurement indicative of blood volume in response to a user action. Themethod further comprises means for obtaining, via the plurality ofsensors, a second measurement indicative of heart electrical activity inresponse to the user action. The method also comprises means forfacilitating, via a processor of the mobile device, generation of ablood pressure measurement based on the first measurement and the secondmeasurement, wherein the processor is contained within the outer body ofthe mobile device, the outer body sized to be portable for the user.

In some embodiments, one or more non-transitory computer-readable mediastoring computer-executable instructions for obtaining at least onebodily function measurement that, when executed, cause one or morecomputing devices included in a mobile device to obtain, via a pluralityof sensors physically coupled to an outer body of the mobile device, afirst measurement indicative of blood volume in response to a useraction. The computer-executable instructions, when executed, furthercause the one or more computing devices included in a device to obtain,via the plurality of sensors, a second measurement indicative of heartelectrical activity in response to the user action. Thecomputer-executable instructions, when executed, further cause the oneor more computing devices included in a device to facilitate, via aprocessor of the mobile device, generation of a blood pressuremeasurement based on the first measurement and the second measurement,wherein the processor is contained within the outer body of the mobiledevice, the outer body sized to be portable for the user.

In some embodiments, a mobile device for obtaining at least one bodilyfunction measurement comprises an outer body sized to be portable for auser, a processor contained within the outer body, and a plurality ofsensors physically coupled to the outer body for obtaining dataaccessible by the processor. The plurality of sensors compriseselectrodes and a portion of a user's body positioned between theelectrodes completes a circuit and a measurement to provide at least onemeasure of impedance associated with the user's body in response to auser action. The processor is configured to facilitate generation of ahydration level measurement based on the measure of impedance.

In some embodiments, the mobile device is configured to perform aprimary function and a secondary function, and wherein the processor isconfigured to facilitate generation of the hydration level measurementas the secondary function of the mobile device.

In some embodiments, at least one of the sensors is built into amultifunction surface, wherein the multifunction surface is configuredto simultaneously obtain the impedance measurement and a user input.

In some embodiments, the multifunction surface comprises silver metal.

In some embodiments, the multifunction surface comprises Indium TinOxide (ITO).

In some embodiments, the mobile device is a watch.

In some embodiments, the mobile device is a smartphone device.

In some embodiments, a method for obtaining at least one bodily functionmeasurement via a mobile device comprises obtaining, via a plurality ofsensors comprising electrodes and physically coupled to an outer body ofthe mobile device, a measurement to provide at least one measure ofimpedance associated with a user's body in response to a user action,wherein a portion of the user's body positioned between the electrodescompletes a circuit. The method also comprises facilitating, via aprocessor of the mobile device, generation of a hydration levelmeasurement based on the measure of impedance, wherein the processor iscontained within the outer body of the mobile device, the outer bodysized to be portable for the user.

In some embodiments, an apparatus for obtaining at least one bodilyfunction measurement via a mobile device comprises means for obtaining,via a plurality of sensors comprising electrodes and physically coupledto an outer body of the mobile device, a measurement to provide at leastone measure of impedance associated with a user's body in response to auser action, wherein a portion of the user's body positioned between theelectrodes completes a circuit. The apparatus further comprises meansfor facilitating, via a processor of the mobile device, generation of ahydration level measurement based on the measure of impedance, whereinthe processor is contained within the outer body of the mobile device,the outer body sized to be portable for the user.

In some embodiments, one or more non-transitory computer-readable mediastoring computer-executable instructions for obtaining at least onebodily function measurement that, when executed, cause one or morecomputing devices included in a mobile device to obtain, via a pluralityof sensors comprising electrodes and physically coupled to an outer bodyof the mobile device, a measurement to provide at least one measure ofimpedance associated with a user's body in response to a user action,wherein a portion of the user's body positioned between the electrodescompletes a circuit. The computer-executable instructions, whenexecuted, further cause the one or more computing devices included in adevice to facilitate, via a processor of the mobile device, generationof a hydration level measurement based on the measure of impedance,wherein the processor is contained within the outer body of the mobiledevice, the outer body sized to be portable for the user.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the disclosure are illustrated by way of example. In theaccompanying figures, like reference numbers indicate similar elements,and:

FIG. 1 illustrates a smartphone device configured to obtain PPG and ECGmeasurements of a user, according to some embodiments;

FIG. 2 illustrates a smartphone device configured to obtain PPG and ECGmeasurements of a user, according to some embodiments;

FIG. 3 illustrates a wristwatch device configured to obtain PPG, ECG,and impedance measurements of a user, according to some embodiments;

FIG. 4 illustrates a cross sectional view of the wristwatch device ofFIG. 3 and graphs showing measurements obtained by the wristwatchdevice, according to some embodiments;

FIG. 5 a schematic diagram of a mobile device configured to obtainimpedance measurements of a user, according to some embodiments;

FIG. 6 is a schematic diagram of two resistors and a capacitorrepresenting conduction through tissue, according to some embodiments;

FIG. 7 is a flow diagram illustrating a plurality of derived metricsfrom a plurality of sensor metrics, according to some embodiments;

FIG. 8 is a flow diagram of an exemplary method of obtaining at leastone bodily function measurement;

FIG. 9 is another flow diagram of an exemplary method of obtaining atleast one bodily function measurement; and

FIG. 10 illustrates an example of a computing system in which one ormore embodiments may be implemented.

DETAILED DESCRIPTION

Several illustrative embodiments will now be described with respect tothe accompanying drawings, which form a part hereof. While particularembodiments, in which one or more aspects of the disclosure may beimplemented, are described below, other embodiments may be used andvarious modifications may be made without departing from the scope ofthe disclosure or the spirit of the appended claims.

FIG. 1 illustrates a simplified block diagram of a mobile device 100that may incorporate one or more embodiments. Mobile device 100 includesa processor 110, microphone 120, display 130, input device 140, speaker150, memory 160, camera 170, sensors 180, light source 185, andcomputer-readable medium 190.

Processor 110 may be any general-purpose processor operable to carry outinstructions on the mobile device 100. The processor 110 is coupled toother units of the mobile device 100 including microphone 120, display130, input device 140, speaker 150, memory 160, camera 170, sensors 180,light source 185, and computer-readable medium 190.

Microphone 120 may be any an acoustic-to-electric transducer or sensorthat converts sound into an electrical signal. The microphone 120 mayprovide functionality for a user of the mobile device 100 to recordaudio or issue voice commands for the mobile device 100.

Display 130 may be any device that displays information to a user.Examples may include an LCD screen, CRT monitor, or seven-segmentdisplay.

Input device 140 may be any device that accepts input from a user.Examples may include a keyboard, keypad, or mouse. In some embodiments,the microphone 120 may also function as an input device 140.

Speaker 150 may be any device that outputs sound to a user. Examples mayinclude a built-in speaker or any other device that produces sound inresponse to an electrical audio signal and/or ultrasonic signal(s).

Memory 160 may be any magnetic, electronic, or optical memory. Memory160 includes two memory modules, module 1 162 and module 2 164. It canbe appreciated that memory 160 may include any number of memory modules.An example of memory 160 may be dynamic random access memory (DRAM).

Camera 170 is configured to capture one or more images via a lenslocated on the body of mobile device 100. The captured images may bestill images or video images. The camera 170 may include a CMOS imagesensor to capture the images. Various applications running on processor110 may have access to camera 170 to capture images. It can beappreciated that camera 170 can continuously capture images without theimages actually being stored within the mobile device 100. Capturedimages may also be referred to as image frames.

Sensors 180 may be a plurality of sensors configured to obtain dataaccessible by the processor. The sensors 180 may also be physicallycoupled to the outer body of the mobile device 100. The plurality ofsensors 180 may include one or more light sensors 182 and/or one or moreelectrodes 184. The light sensors 182 may be configured to facilitatemeasurement of reflected light from the light source 185 (describedbelow) reflected off of blood vessels within a user of the mobile device100 to obtain the a PPG measurement indicative of the user's bloodvolume. A portion of a user of the mobile device's 100 body may completea circuit between a first electrode and a second electrode, e.g., whenthe user touches both electrodes 184. The electrodes 184 may beconfigured to facilitate measurement of heart electrical activity of theuser to obtain an ECG measurement. The electrodes 184 may also beconfigured to facilitate measurement of impedance of the user of themobile device 100 to obtain a level measurement.

Light source 185 may be any source of light configured to emit lightthrough a user's body. In some embodiments, the light source 185 may bea LED light source. The emitted light may be of a wavelength that canpass through parts of a user's body. For example, the light source 185may emit LED light through a user's wrist. In some embodiments, themobile device 100 may include multiple light sources 185. The lightemitted from light source 185 may reflect off of blood vessels withinthe user's body and the reflected light may be measured by one or morelight sensors 182 to obtain a PPG measurement, as described above. Itcan be appreciated that emitted light may be of different wavelengthsdepending on different wavelengths. For example, different wavelengthsof light may be appropriate to improve the signal, reduce noise, dealwith dark skin colors, measure the blood's oxygen content, or penetrateto different depths of the user's body.

Computer-readable medium 190 may be any magnetic, electronic, optical,or other computer-readable storage medium. Computer-readable storagemedium 190 includes PPG measurement module 192, ECG measurement module194, blood pressure measurement module 196, impedance measurement module198, and hydration level measurement module 199.

PPG measurement module 192 is configured to, when executed by processor110, obtain a photoplethysmography (PPG) measurement. The PPGmeasurement may be a measurement of blood volume of a user operating themobile device 100. The PPG measurement may be obtained by the PPGmeasurement module 192 in response to a user action. The PPG measurementmodule 192 may interface with the light source 185 and light sensors 182in order to obtain the PPG measurement. Upon indication by the user of aneed for a PPG measurement, the PPG measurement module 192 may directthe light source 185, or multiple light sources, to emit light throughthe user's body. As described above, the emitted light may reflect offor transmitted through blood vessels within the user's body and may bedetected by one or more light sensors 182 within the mobile device 100.The PPG measurement module 192 may measure, by interfacing with the oneor more light sensors, the amount of reflected or transmitted lightdetected by the one or more light sensors 182. The PPG measurementmodule 192 may then determine a PPG measurement that is indicative ofthe user's blood volume based on the measurement of the reflected light.

ECG measurement module 194 is configured to, when executed by processor110, obtain an electrocardiography (ECG) measurement. The ECGmeasurement may be a measurement of heart electrical activity of a useroperating the mobile device 100. The ECG measurement may be obtained bythe ECG measurement module 194 in response to a user action. The ECGmeasurement module 194 may interface with the electrodes 184 in order toobtain the ECG measurement. Upon indication by the user of a need for anECG measurement, the ECG measurement module 194 may interface with theelectrodes 184 to measure (assuming the user's body completes a circuitbetween the electrodes 184) electrical impulse(s) generated by thepolarization and depolarization of cardiac tissue within the user'sbody. In some embodiments, the electrical impulse(s) may be generated bythe beating of the user's heart. In some embodiments, the ECGmeasurement module 194 may interface with the electrodes 184 to measurethe electrical impulse(s) automatically upon the user's body completinga circuit between the electrodes 184. The ECG measurement module 194 maythen determine an ECG measurement based on the measured electricalimpulse(s). It can be appreciated that ECG measurement can be obtainedusing two or more electrode leads.

Blood pressure measurement module 196 is configured to, when executed byprocessor 110, generate a blood pressure measurement of the user basedon the PPG measurement and the ECG measurement. According to Poon, C. C.Y.; Zhang, Y. T. “Cuff-less and Noninvasive Measurements of ArterialBlood Pressure by Pulse Transit Time”, Engineering in Medicine andBiology 27^(th) Annual Conference, 2005. IEEE, On page(s): 1-4, thecalculation of the blood pressure measurement based on the PPGmeasurement and the ECG measurement is well known in the art.

Impedance measurement module 198 is configured to, when executed byprocessor 110, obtain an impedance measurement. The impedancemeasurement may be indicative of a hydration level of a user operatingthe mobile device 100. The impedance measurement may be obtained by theimpedance measurement module 198 in response to a user action. Inimpedance measurement module 198 may interface with the electrodes 184in order to obtain the impedance measurement. Upon indication by theuser of a need for an impedance measurement, the impedance measurementmodule 198 may interface with the electrodes 184 to measure (assumingthe user's body completes a circuit between the electrodes 184)electrical impedance through the user's body. In some embodiments, theimpedance measurement module 198 may interface with the electrodes 184to measure the electrical impedance automatically upon the user's bodycompleting a circuit between the electrodes 184.

Hydration level measurement module 199 is configured to, when executedby processor 110, obtain a hydration level measurement based on theimpedance measurement obtained by the impedance measurement module 198.The hydration level measurement module 199 may determine the hydrationlevel from the measured impedance using techniques well known in theart.

It can be appreciated that the outer body of the mobile device 100 maybe sized to be portable for a user. It can be appreciated that the term“portable” may refer to something that is able to be easily carried ormoved, and may be a light and/or small. In the context of embodiments ofthe present invention, the term portable may refer to something easilytransportable by the user or wearable by the user. For example, themobile device 100 may be a smartphone device or a watch wearable by theuser. Other examples of portable devices include a head-mounted display,calculator, portable media player, digital camera, pager, personalnavigation device, etc. Examples of devices that may not be consideredportable include a desktop computer, traditional telephone, television,appliances, etc. It can be appreciated that the bodily functionmeasurements can be obtained via the smartphone, watch, or any other ofthe mentioned devices.

FIG. 2 illustrates a smartphone device 210 configured to obtain PPG andECG measurements of a user, according to some embodiments. It can beappreciated that the smartphone device 210 is only one example of amobile device 100. The smartphone device 210 may include a plurality ofcontacts 220. In some embodiments, a single contact 220 may bepositioned at each end of the smartphone device 210. In otherembodiments, a device front surface 250 of the smartphone device 210 mayinclude a contact layer including, e.g., silver metal or Indium TinOxide (ITO). The smartphone device 210 may obtain both PPG and ECGmeasurements of the user 260. In some embodiments, the device frontsurface 250 may be a touchscreen.

For example, the user 260 may hold the smartphone device 210 withhis/her first hand 240 touching one or more of the contacts 220 and withhis/her second hand 230 touching the device front surface 250. Upon theuser 260 performing this action, the contacts 220 and the contact layerof the device front surface 250 may complete a circuit through theuser's 260 body. The smartphone device 210 may then measure anelectrical potential through the completed circuit to determine the ECGmeasurement. It can be appreciated that the ECG measurement may also beobtained without the user's first hand 240 or second hand 230 contactingthe device front surface 250. That is, the user's first hand 240 maymake contact with a first side contact 220 and the user's second hand230 may make contact with a second side contact 220 to complete thecircuit. Alternatively, the user 260 may make contact with both sidecontacts 220 using only his/her first hand 240 or second hand 230 (seebelow for a measurement of PPG or Galvanic Skin Response (GSR)).Alternatively, and not illustrated in FIG. 1, sensors positioned and/ortouched at other locations, for example legs, feet, ankles, knees,elbows, arms, neck, head, etc. could also be used to generate PPG, GSRand possibly ECG, depending on the location and how the contact wasmade.

The device front surface 250 of the smartphone device 210 may alsoobtain a PPG measurement of the user 260 by using an optical basedtechnology. For example, when the user 260 touches the device frontsurface 250, the touchscreen may shine a light into the user's 260 skin,measure the blood flow through the capillaries and thus determine aheart rate (PPG) of the user. This process is described in furtherdetail below.

Accordingly, by obtaining both the PPG and ECG measurements of the user260, a PTT technique may be used to determine the user's blood pressure.The smartphone device 210 may then provide important information to theuser 260, based on the determined blood pressure (described furtherbelow).

Additionally, the smartphone device 210 may obtain an impedancemeasurement of the user using BIA techniques. In some embodiments, theimpedance measurement may be obtained via the contact layer of thedevice front surface 250. The process of obtaining the impedancemeasurement is described in further detail below.

It can be appreciated that the device front surface 250 may servemultiple functions. That is, the device front surface 250 may be used toobtain ECG, PPG, and/or impedance measurements as described above, andmay also be used as a user input device. The user 260 may use the devicefront surface 250 to provide input to applications being executed on thesmartphone device 210. When the user 260 wishes to obtain a bodilyfunction measurement using the device front surface 250, the user 260may place the smartphone device 210 into a measurement mode.Alternatively, the smartphone device 210 may automatically detect theuser's intention to obtain a bodily function measurement, e.g., from theuser 260 placing his/her finger in a particular location on the devicefront surface 250 or touching the device front surface 250 for apredetermined period of time. Alternatively, the smartphone device 210may regularly scan and store vital signs of the user 260 in the user'snormal course of operating the device 210, without the user wanting orneeded a particular vital sign report at that time.

FIG. 3 illustrates a wristwatch device 310 configured to obtain PPG,ECG, and impedance measurements of a user, according to someembodiments. The wristwatch device 310 illustrated in FIG. 3 operatessimilarly to the smartphone device 210 in FIG. 2. That is, thewristwatch device 310 may obtain PPG, ECG, and impedance measurements ofthe user 260 via a plurality of contacts. In some embodiments, one ormore contacts may be placed at the bottom of the wristwatch device 310,where the contact makes a continuous contact with the user's 260 wristwhile the user 260 wears the wristwatch device 310.

The wristwatch device 310 may also include a multifunction button 320,which may be used to obtain a bodily function measurement and also as auser input device. For example, the multifunction button 320 may be usedby the user 260 to set a date and/or time for the wristwatch device 310.The multifunction button may have an integrated electrode on thesurface. The user 260 may also use the multifunction button 320 toobtain an ECG measurement by touching the button 320 to complete acircuit (via the other contacts) through the user's body. In someembodiments, the multifunction button 320 may be integrated into atouchscreen of the wristwatch device 310.

The PPG and hydration measurements may be obtained in a similar fashionas described with respect to the smartphone device of FIG. 2, e.g., viathe contacts on the wristwatch device 310. The PPG measurement may alsobe obtained using optical techniques, as described below.

The wristwatch device 310 may be designed to be portable such that theuser may easily wear the device or carry it on his/her person. In someembodiments, the wristwatch device 310 may perform everyday functionsother than obtaining PPG, ECG, and impedance measurements of the user.For example, the wristwatch device 310 may provide the current time, astopwatch function, a calendar function, communication functions, etc.The PPG, ECG, and impedance measurements functions may be available inaddition to the other described functions on the wristwatch device 310.

FIG. 4 illustrates a cross sectional view 410 of the wristwatch device310 of FIG. 3 and graphs 420, 430, and 440 showing measurements obtainedby the wristwatch device, according to some embodiments. The crosssectional view 410 of the wristwatch device 310 shows a photodetector412, a plurality of light emitting diodes (LED) 414, and a plurality ofelectrodes contacts 416. Additionally, the cross sectional view 410 alsoillustrates parts of a user's wrist, e.g., radial bone 418 and ulnarbone 419.

The wristwatch device 310 may obtain PPG measurements of the user byusing optical techniques. To obtain a PPG measurement, the LEDs 414(typically positioned at the bottom of the wristwatch device 310 and ontop of the user's wrist) may emit a light into the user's skin. Thereflected light may be received at the photodetector 412. The user'sblood volume may be determined based off of the reflected light ascompared against time. From this data, the user's PPG measurement may bedetermined. In some embodiments, the determination of the user's bloodvolume may be determined from a change in the user's blood volume. Morespecifically, a change in the diameter of the blood vessels that arebeing probed by the LEDs 414.

Additionally, the user's ECG measurement may be obtained using theplurality of contacts 416 as described above with respect to FIG. 3. Itcan be appreciated that in the wristwatch device 310 embodiment, theplurality of contacts 416 may continuously be in contact with the user'sskin while the user is wearing the wristwatch device 310 around his/herwrist. The user may then touch, with his/her hand that is not wearingthe wristwatch device 310, another contact 416 that is located atanother location on the wristwatch device 310 to complete the circuitthrough the user's body.

Similarly, the user's hydration measurements may also be obtained byusing the plurality of contacts 416 and determining impedance throughthe user's body.

Graph 420 illustrates the intensity of the obtained light reflections atthe photodetector 412 against time. In this example, the durationbetween each pulse is approximately one second. From this graph, theuser's PPG can be determined.

Graph 430 shows a user's heart rate variability by comparing the user'sECG and the user's PPG. As shown in graph 440, the PTT can be determinedby taking the difference between a peak of an ECG pulse and thecorresponding inflection point (at the same time interval) of the PPGpulse. The PTT may then be used to determine the user's blood pressure,which is well known in the art.

FIG. 5 is a schematic diagram 500 of a mobile device configured toobtain impedance measurements of a user, according to some embodiments.The mobile device may be either the smartphone device described in FIG.2, the wristwatch device described in FIG. 3, or any other mobiledevice. As described above, the impedance measurement of the user may beused to determine the user's hydration level using BIA techniques. Theuser's body 510 essentially functions as a capacitance and resistancenetwork in this illustration. When the user's body 510 makes contactwith the contact points 530, an impedance converter 520 may determinethe impedance value through the user's body 510. In this scenario, theuser's body 510 may act as a capacitor. The impedance value may be afunction of surface tissue impedance and deep tissue impedance. Theimpedance value may then be used to estimate a total body water contentof the user's body 510. This figure shows measuring the impedancethrough one leg, the torso, and one arm. The method works the same waymeasuring through both arms and the chest. In some embodiments, themobile device may include phase-sensitive electronics to distinguishbetween electrical resistance and reactance.

Upon determining the user's hydration level, the mobile device mayprovide a notification to the user. The types of notifications aredescribed in further detail with respect to FIG. 7.

FIG. 6 is a schematic diagram 600 of two resistors and a capacitorrepresenting conduction through tissue, according to some embodiments.In FIG. 6, x_(c) represents the capacitance of the user's cell walls,R_((ICW)) represents the resistance of the body water inside of theuser's cells, and R_((ECW)) represents the resistance of the body wateroutside of the user's cells. The circuit shown in FIG. 6 may be used aspart of the schematic diagram in FIG. 5 to determine the hydration levelof the user by determining an electrical impedance through the user'sbody.

FIG. 7 is a flow diagram 700 illustrating a plurality of derived metrics720 from a plurality of sensor metrics 710, according to someembodiments. The plurality of sensor metrics 710 may include, but is notlimited to, PPG pulse measurement, accelerometer measurements, ACbiometric impedance measurements, and 2-lead ECG heart ratemeasurements. These sensor metrics 710 may be obtained by takingmeasurements via the mobile device. Based on data from the sensormetrics 710, a plurality of derived metrics 720 may be derived. Thesederived metrics may include, but is not limited to, heart rate, heartrate variability, stress calculation, blood pressure, and hydrationstate.

For example, when a PPG pulse measurement is obtained, using thetechniques described herein, the user's heart rate and/or heart ratevariability may be determined. The PPG pulse measurement may be combinedwith an ECG heart rate measurement to determine the user's bloodpressure using PTT techniques. Based on the determined blood pressure, auser's stress level may be determined. If it is determined that the useris at a high stress level, the mobile device may notify the user to takea deep breath, go for a walk, drink a glass of water, etc. As shown, thestress level may also be determined from the user's GSR data.

In another example, when an AC bioelectric impedance measurement isobtained, using the techniques described herein, the user's hydrationstate may be determined from data regarding the total body water of theuser. If the user's hydration state is determined to be low, the mobiledevice may notify the user to drink a glass of water. On the other hand,if the user's hydration state is determined to be adequate, the mobiledevice may notify the user that to keep up the good work.

In another example, energy calculations may be determined based uponaccelerometer and gyroscope data obtained by the mobile device. Forexample, if the user is moving around actively, the accelerometer datamay indicate a high level of movement and the mobile device maydetermine that the user's energy level is high. The mobile device maynotify the user to continue being active. In some embodiments, themobile device may keep track of the user's energy level throughout theday and notify the user upon predetermined intervals to become active inorder to reach a threshold amount of activity for the day.

In some embodiments, accelerometer measurements may be used to determinethe user's heart rate and/or heart rate variability. The samecalculations described above may determined/calculated using thesemeasurements.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Further, somesteps may be combined or omitted. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Moreover, nothing disclosed herein is intended to bededicated to the public.

FIG. 8 is a flow diagram 800 of an exemplary method of obtaining atleast one bodily function measurement. In block 810, a first measurementindicative of blood volume is obtained in response to a user action. Thefirst measurement may be obtained via a plurality of sensors physicallycoupled to an outer body of a mobile device. In some embodiments, thefirst measurement may be a photoplethysmography (PPG) measurement.

In some embodiments, the plurality of sensors may include at least onelight sensor. The mobile device may also include at least one lightsource. Obtaining the first measurement may include measuring, via theat least one light sensor, reflected light from the light sourcereflected off of blood vessels within a user of the mobile device. Forexample, in FIG. 3, the wearable watch obtains a PPG measurement of theuser via the light sensors and light source within the wearable watch.The PPG measurement may be obtained by the PPG measurement moduledescribed in FIG. 1.

In block 820, a second measurement indicative of heart electricalactivity is obtained in response to the user action. The secondmeasurement may be obtained via the plurality of sensors. In someembodiments, the second measurement may be an electrocardiography (ECG)measurement.

In some embodiments, the plurality of sensors may include at least afirst electrode and a second electrode. Obtaining the second measurementmay include detecting completion of a circuit between the firstelectrode and the second electrode via a portion of the user's body. Forexample, in FIG. 3, the wearable watch obtains an ECG measurement of theuser via the electrodes located on the outer body of the wearable watch.The ECG measurement may be obtained by the ECG measurement moduledescribed in FIG. 1.

In block 830, generation of a blood pressure measurement based on thefirst measurement and the second measurement is facilitated via aprocessor of the mobile device. The processor may be contained withinthe outer body of the mobile device and the outer body may be sized tobe portable for the user. In some embodiments, the mobile device may beconfigured to perform a primary function and a secondary function.Facilitating the generation of the blood pressure measurement may beperformed as the secondary function of the mobile device. For example,in FIG. 3, the wearable watch may facilitate measurement of the user'sblood pressure based on the obtained PPG and ECG measurements. The bloodpressure may be determined by the blood pressure measurement moduledescribed in FIG. 1.

In some embodiments, the mobile device is a watch. For example, in FIG.3, the mobile device is a wearable watch. In other embodiments, themobile device is a smartphone device. For example, in FIG. 2, the mobiledevice is a smartphone device.

In some embodiments, at least one of the sensors is built into amultifunction surface, wherein the multifunction surface is configuredto simultaneously obtain the first measurement or the second measurementand a user input. For example, in FIG. 2, the smartphone device (alsocapable of obtaining PPG and ECG measurements similar to the wearablewatch) includes a multifunction touchscreen surface that facilitatesuser input to the smartphone device.

In some embodiments, block 810 and block 820 may be performed by a firstdevice and block 830 may be performed by a second device. That is, themeasures of blood volume and heart electrical activity may be performedby a device separate than the generation of the blood pressuremeasurement. For example, the measure of blood volume and heartelectrical activity may be performed via a communication device worn bythe user, whereas the generation of the blood pressure measurement maybe performed by a server computer that receives the measures of bloodvolume and heart electrical activity from the communication device. Insome embodiments, the server computer could reside within a cloudsystem.

FIG. 9 is another flow diagram 900 of an exemplary method of obtainingat least one bodily function measurement. In block 910, a measurement toprovide at least one measure of impedance associated with a user's bodyis obtained in response to a user action. In some embodiments, themeasurement may be obtained via a plurality of sensors comprisingelectrodes that are physically coupled to an outer body of the mobiledevice. In some embodiments, a portion of the user's body positionedbetween the electrodes completes a circuit.

For example, in FIG. 3, the wearable watch obtains an impedancemeasurement of the user via the electrodes located on the outer body ofthe wearable watch. The impedance measurement may be obtained by theimpedance measurement module described in FIG. 1.

In block 920, generation of a hydration level measurement based on themeasure of impedance is facilitated via a processor of the mobiledevice. In some embodiments, the processor is contained within the outerbody of the mobile device. In some embodiments, the outer body is sizedto be portable for the user.

In some embodiments, the mobile device is configured to perform aprimary function and a secondary function. In some embodiments, theprocessor is configured to facilitate generation of the hydration levelmeasurement as the secondary function of the mobile device. For example,in FIG. 3, the wearable watch may facilitate measurement of the user'shydration level based on the obtained impedance measurement. Thehydration level may be determined by the hydration level measurementmodule described in FIG. 1.

In some embodiments, at least one of the sensors is built into amultifunction surface. In some embodiments, the multifunction surface isconfigured to simultaneously obtain the impedance measurement and a userinput. In some embodiments, the multifunction surface comprises IndiumTin Oxide (ITO). In some embodiments, the multifunction surfacecomprises silver metal. In some embodiments, the multifunction surfacecomprises a network of wires or a transparent conductor. For example, inFIG. 2, the smartphone device (also capable of obtaining impedancemeasurements similar to the wearable watch) includes a multifunctiontouchscreen surface that facilitates user input to the smartphonedevice.

In some embodiments, the mobile device is a watch. For example, in FIG.3, the mobile device is a wearable watch. In other embodiments, themobile device is a smartphone device. For example, in FIG. 2, the mobiledevice is a smartphone device.

In some embodiments, block 910 may be performed by a first device andblock 920 may be performed by a second device. That is, the measure ofimpedance may be performed by a device separate than the generation ofthe hydration level measurement. For example, the measure of impedancemay be performed via a communication device worn by the user, whereasthe generation of the hydration level may be performed by a servercomputer that receives the measure of impedance from the communicationdevice. In some embodiments, the server computer could reside within acloud system.

FIG. 10 illustrates an example of a computing system in which one ormore embodiments may be implemented. A computer system as illustrated inFIG. 10 may be incorporated as part of the above described computerizeddevice. For example, computer system 1000 can represent some of thecomponents of a television, a computing device, a server, a desktop, aworkstation, a control or interaction system in an automobile, a tablet,a netbook or any other suitable computing system. A computing device maybe any computing device with an image capture device or input sensoryunit and a user output device. An image capture device or input sensoryunit may be a camera device. A user output device may be a display unit.Examples of a computing device include but are not limited to video gameconsoles, tablets, smart phones and any other hand-held devices. FIG. 10provides a schematic illustration of one embodiment of a computer system1000 that can perform the methods provided by various other embodiments,as described herein, and/or can function as the host computer system, aremote kiosk/terminal, a point-of-sale device, a telephonic ornavigation or multimedia interface in an automobile, a computing device,a set-top box, a table computer and/or a computer system. FIG. 10 ismeant only to provide a generalized illustration of various components,any or all of which may be utilized as appropriate. FIG. 10, therefore,broadly illustrates how individual system elements may be implemented ina relatively separated or relatively more integrated manner. In someembodiments, elements of computer system 100 may be used to implementfunctionality of the mobile device 100 in FIG. 1.

The computer system 1000 is shown comprising hardware elements that canbe electrically coupled via a bus 1002 (or may otherwise be incommunication, as appropriate). The hardware elements may include one ormore processors 1004, including without limitation one or moregeneral-purpose processors and/or one or more special-purpose processors(such as digital signal processing chips, graphics accelerationprocessors, and/or the like); one or more input devices 1008, which caninclude without limitation one or more cameras, sensors, a mouse, akeyboard, a microphone configured to detect ultrasound or other sounds,and/or the like; and one or more output devices 1010, which can includewithout limitation a display unit such as the device used in embodimentsof the invention, a printer and/or the like.

In some implementations of the embodiments of the invention, variousinput devices 1008 and output devices 1010 may be embedded intointerfaces such as display devices, tables, floors, walls, and windowscreens. Furthermore, input devices 1008 and output devices 1010 coupledto the processors may form multi-dimensional tracking systems.

The computer system 1000 may further include (and/or be in communicationwith) one or more non-transitory storage devices 1006, which cancomprise, without limitation, local and/or network accessible storage,and/or can include, without limitation, a disk drive, a drive array, anoptical storage device, a solid-state storage device such as a randomaccess memory (“RAM”) and/or a read-only memory (“ROM”), which can beprogrammable, flash-updateable and/or the like. Such storage devices maybe configured to implement any appropriate data storage, includingwithout limitation, various file systems, database structures, and/orthe like.

The computer system 1000 might also include a communications subsystem1012, which can include without limitation a modem, a network card(wireless or wired), an infrared communication device, a wirelesscommunication device and/or chipset (such as a Bluetooth™ device, an802.11 device, a Wi-Fi device, a WiMax device, cellular communicationfacilities, etc.), and/or the like. The communications subsystem 1012may permit data to be exchanged with a network, other computer systems,and/or any other devices described herein. In many embodiments, thecomputer system 1000 will further comprise a non-transitory workingmemory 1018, which can include a RAM or ROM device, as described above.

The computer system 1000 also can comprise software elements, shown asbeing currently located within the working memory 1018, including anoperating system 1014, device drivers, executable libraries, and/orother code, such as one or more application programs 1016, which maycomprise computer programs provided by various embodiments, and/or maybe designed to implement methods, and/or configure systems, provided byother embodiments, as described herein. Merely by way of example, one ormore procedures described with respect to the method(s) discussed abovemight be implemented as code and/or instructions executable by acomputer (and/or a processor within a computer); in an aspect, then,such code and/or instructions can be used to configure and/or adapt ageneral purpose computer (or other device) to perform one or moreoperations in accordance with the described methods.

A set of these instructions and/or code might be stored on acomputer-readable storage medium, such as the storage device(s) 1006described above. In some cases, the storage medium might be incorporatedwithin a computer system, such as computer system 1000. In otherembodiments, the storage medium might be separate from a computer system(e.g., a removable medium, such as a compact disc), and/or provided inan installation package, such that the storage medium can be used toprogram, configure and/or adapt a general purpose computer with theinstructions/code stored thereon. These instructions might take the formof executable code, which is executable by the computer system 1000and/or might take the form of source and/or installable code, which,upon compilation and/or installation on the computer system 1000 (e.g.,using any of a variety of generally available compilers, installationprograms, compression/decompression utilities, etc.) then takes the formof executable code.

Substantial variations may be made in accordance with specificrequirements. For example, customized hardware might also be used,and/or particular elements might be implemented in hardware, software(including portable software, such as applets, etc.), or both. Further,connection to other computing devices such as network input/outputdevices may be employed. In some embodiments, one or more elements ofthe computer system 1000 may be omitted or may be implemented separatefrom the illustrated system. For example, the processor 1004 and/orother elements may be implemented separate from the input device 1008.In one embodiment, the processor is configured to receive images fromone or more cameras that are separately implemented. In someembodiments, elements in addition to those illustrated in FIG. 10 may beincluded in the computer system 1000.

Some embodiments may employ a computer system (such as the computersystem 1000) to perform methods in accordance with the disclosure. Forexample, some or all of the procedures of the described methods may beperformed by the computer system 1000 in response to processor 1004executing one or more sequences of one or more instructions (which mightbe incorporated into the operating system 1014 and/or other code, suchas an application program 1016) contained in the working memory 1018.Such instructions may be read into the working memory 1018 from anothercomputer-readable medium, such as one or more of the storage device(s)1006. Merely by way of example, execution of the sequences ofinstructions contained in the working memory 1018 might cause theprocessor(s) 1004 to perform one or more procedures of the methodsdescribed herein.

The terms “machine-readable medium” and “computer-readable medium,” asused herein, refer to any medium that participates in providing datathat causes a machine to operate in a specific fashion. In someembodiments implemented using the computer system 1000, variouscomputer-readable media might be involved in providing instructions/codeto processor(s) 1004 for execution and/or might be used to store and/orcarry such instructions/code (e.g., as signals). In manyimplementations, a computer-readable medium is a physical and/ortangible storage medium. Such a medium may take many forms, includingbut not limited to, non-volatile media, volatile media, and transmissionmedia. Non-volatile media include, for example, optical and/or magneticdisks, such as the storage device(s) 1006. Volatile media include,without limitation, dynamic memory, such as the working memory 1018.Transmission media include, without limitation, coaxial cables, copperwire and fiber optics, including the wires that comprise the bus 1002,as well as the various components of the communications subsystem 1012(and/or the media by which the communications subsystem 1012 providescommunication with other devices). Hence, transmission media can alsotake the form of waves (including without limitation radio, acousticand/or light waves, such as those generated during radio-wave andinfrared data communications).

Common forms of physical and/or tangible computer-readable mediainclude, for example, a floppy disk, a flexible disk, hard disk,magnetic tape, or any other magnetic medium, a CD-ROM, any other opticalmedium, punchcards, papertape, any other physical medium with patternsof holes, a RAM, a PROM, EPROM, a FLASH-EPROM, any other memory chip orcartridge, a carrier wave as described hereinafter, or any other mediumfrom which a computer can read instructions and/or code.

Various forms of computer-readable media may be involved in carrying oneor more sequences of one or more instructions to the processor(s) 1004for execution. Merely by way of example, the instructions may initiallybe carried on a magnetic disk and/or optical disc of a remote computer.A remote computer might load the instructions into its dynamic memoryand send the instructions as signals over a transmission medium to bereceived and/or executed by the computer system 1000. These signals,which might be in the form of electromagnetic signals, acoustic signals,optical signals and/or the like, are all examples of carrier waves onwhich instructions can be encoded, in accordance with variousembodiments of the invention.

The communications subsystem 1012 (and/or components thereof) generallywill receive the signals, and the bus 1002 then might carry the signals(and/or the data, instructions, etc. carried by the signals) to theworking memory 1018, from which the processor(s) 1004 retrieves andexecutes the instructions. The instructions received by the workingmemory 1018 may optionally be stored on a non-transitory storage device1006 either before or after execution by the processor(s) 1004.

The methods, systems, and devices discussed above are examples. Variousconfigurations may omit, substitute, or add various procedures orcomponents as appropriate. For instance, in alternative configurations,the methods may be performed in an order different from that described,and/or various stages may be added, omitted, and/or combined. Also,features described with respect to certain configurations may becombined in various other configurations. Different aspects and elementsof the configurations may be combined in a similar manner. Also,technology evolves and, thus, many of the elements are examples and donot limit the scope of the disclosure or claims.

Specific details are given in the description to provide a thoroughunderstanding of example configurations (including implementations).However, configurations may be practiced without these specific details.For example, well-known circuits, processes, algorithms, structures, andtechniques have been shown without unnecessary detail in order to avoidobscuring the configurations. This description provides exampleconfigurations only, and does not limit the scope, applicability, orconfigurations of the claims. Rather, the preceding description of theconfigurations will provide those skilled in the art with an enablingdescription for implementing described techniques. Various changes maybe made in the function and arrangement of elements without departingfrom the spirit or scope of the disclosure.

Also, configurations may be described as a process which is depicted asa flow diagram or block diagram. Although each may describe theoperations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be rearranged. A process may have additional steps notincluded in the figure. Furthermore, examples of the methods may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware, or microcode, the programcode or code segments to perform the necessary tasks may be stored in anon-transitory computer-readable medium such as a storage medium.Processors may perform the described tasks.

Having described several example configurations, various modifications,alternative constructions, and equivalents may be used without departingfrom the spirit of the disclosure. For example, the above elements maybe components of a larger system, wherein other rules may takeprecedence over or otherwise modify the application of the invention.Also, a number of steps may be undertaken before, during, or after theabove elements are considered.

What is claimed is:
 1. A wearable device comprising: an outer bodyshaped as a part of a wristwatch and configured to be wearable on awrist of a user; a first sensor coupled to the outer body and positionedto be in contact with the user when the wearable device is used by theuser, the first sensor configured to transmit first sensor signals; asecond sensor coupled to the outer body and comprising a plurality ofelectrodes, the second sensor positioned to be in contact with the userwhen the wearable device is used by the user and configured to transmitsecond sensor signals based on a user interaction with at least twoelectrodes of the plurality of electrodes; a multifunction surface ormultifunction button configured to detect one or more user interactions;and a processor positioned within the outer body and coupled to thefirst and second sensors, the processor configured to: detect aninteraction with the multifunction surface or multifunction button; inresponse to detecting the interaction with the multifunction surface ormultifunction button, transitioning the wearable device into ameasurement mode from a normal course of operation; and in response tothe wearable device transitioning into the measurement mode from thenormal course of operation, determine a bodily function measurementbased on the first sensor signals and the second sensor signals, thebodily function measurement including at least one of a stress level ofthe user, a blood pressure of the user, a blood volume of the user, ahydration level of the user, and a heart electrical activity in theuser.
 2. The wearable device of claim 1, wherein the first sensorsignals indicate the blood volume within the user and the second sensorsignals indicate the heart electrical activity in the user.
 3. Thewearable device of claim 2, wherein the first sensor comprises one ormore light sources and one or more light sensors.
 4. The wearable deviceof claim 1, wherein the second sensor signals indicate the hydrationlevel of the user.
 5. The wearable device of claim 1, wherein themultifunction surface comprises at least one electrode of the at leasttwo electrodes.
 6. The wearable device of claim 1, wherein a firstelectrode of the at least two electrodes is positioned at one end of thewearable device and a second electrode of the at least two electrodes ispositioned at an opposite end of the wearable device.
 7. The wearabledevice of claim 1, wherein a first electrode of the at least twoelectrodes is positioned on a surface of the wearable device configuredto be worn against skin of the user and a second electrode of the atleast two electrodes is positioned on the multifunction surface.
 8. Thewearable device of claim 1, wherein the processor is configured todetermine the bodily function measurement based on a pulse-transit-time(PTT) technique.
 9. The wearable device of claim 8, wherein theprocessor is further configured to: determine a photoplethysmography(PPG) measurement based on the first sensor signals; determine anelectrocardiogram (ECG) measurement based on the second sensor signals;and determine a PTT using the PPT technique based on the PPG measurementand the ECG measurement, and wherein the bodily function measurement isbased on the PTT.
 10. The wearable device of claim 1, wherein the bodilyfunction measurement comprises the stress level of the user, and whereinthe processor is further configured to output a notification indicatingthe user should take a deep breath based on the stress level.
 11. Amethod for obtaining at least one bodily function measurementcomprising: detecting an interaction with a multifunction surface ormultifunction button of a wearable device, the wearable devicecomprising: an outer body shaped as a part of a wristwatch andconfigured to be wearable on a wrist of a user; a first sensor coupledto the outer body and positioned to be in contact with the user when thewearable device is used by the user, the first sensor configured totransmit first sensor signals; a second sensor coupled to the outer bodyand comprising a plurality of electrodes, the second sensor positionedto be in contact with the user when the wearable device is used by theuser and configured to transmit second sensor signals based on a userinteraction with at least two electrodes of the plurality of electrodes;the multifunction surface or multifunction button configured to detectone or more user interactions; transitioning, by a processor, into ameasurement mode from a normal course of operation of the wearabledevice based on the interaction with the multifunction surface ormultifunction button; receiving, in the measurement mode by theprocessor, the first sensor signals and the second sensor signals; anddetermining, in the measurement mode by the processor, a bodily functionmeasurement based on the first sensor signals and the second sensorsignals, the bodily function measurement including at least one of astress level of the user, a blood pressure of the user, a blood volumeof the user, a hydration level of the user, and a heart electricalactivity in the user.
 12. The method of claim 11, wherein the firstsensor signals indicate the blood volume within the user and the secondsensor signals indicate the heart electrical activity in the user. 13.The method of claim 11, wherein the first sensor comprises one or morelight sources and one or more light sensors.
 14. The method of claim 11,wherein the second sensor signals indicate the hydration level of theuser.
 15. The method of claim 11, wherein the multifunction surfacecomprises at least one electrode of the at least two electrodes.
 16. Themethod of claim 11, wherein a first electrode of the at least twoelectrodes is positioned at one end of the wearable device and a secondelectrode of the at least two electrodes is positioned at an oppositeend of the wearable device.
 17. The method of claim 11, wherein a firstelectrode of the at least two electrodes is positioned on a surface ofthe wearable device configured to be worn against skin of the user and asecond electrode of the at least two electrodes is positioned on themultifunction surface.
 18. The method of claim 11, wherein determiningthe bodily function measurement is based on a pulse-transit-time (PTT)technique.
 19. The method of claim 11, further comprising: determining aphotoplethysmography (PPG) measurement based on the first sensorsignals; determining an electrocardiogram (ECG) measurement based on thesecond sensor signals; and determining a PTT using the PPT techniquebased on the PPG measurement and the ECG measurement, and wherein thebodily function measurement is based on the PTT.
 20. The method of claim11, wherein the bodily function measurement comprises the stress levelof the user, and further comprising outputting a notification indicatingthe user should take a deep breath based on the stress level.
 21. Anon-transitory computer-readable medium comprising processor-executableinstructions configured to cause a processor to: detect an interactionwith a multifunction surface or multifunction button of a wearabledevice, the wearable device comprising: an outer body shaped as a partof a wristwatch and configured to be wearable on a wrist of a user; afirst sensor coupled to the outer body and positioned to be in contactwith the user when the wearable device is used by the user, the firstsensor configured to transmit first sensor signals; a second sensorcoupled to the outer body and comprising a plurality of electrodes, thesecond sensor positioned to be in contact with the user when thewearable device is used by the user and configured to transmit secondsensor signals based on a user interaction with at least two electrodesof the plurality of electrodes; the multifunction surface ormultifunction button configured to detect one or more user interactions;transition into a measurement mode from a normal course of operation ofthe wearable device based on the interaction with the multifunctionsurface or multifunction button; receive, in the measurement mode, thefirst sensor signals and the second sensor signals; and determine, inthe measurement mode, a bodily function measurement based on the firstsensor signals and the second sensor signals, the bodily functionmeasurement including at least one of a stress level of the user, ablood pressure of the user, a blood volume of the user, a hydrationlevel of the user, and a heart electrical activity in the user.
 22. Thenon-transitory computer-readable medium of claim 21, wherein the firstsensor signals indicate the blood volume within the user and the secondsensor signals indicate the heart electrical activity in the user. 23.The non-transitory computer-readable medium of claim 21, wherein thefirst sensor comprises one or more light sources and one or more lightsensors.
 24. The non-transitory computer-readable medium of claim 21,wherein the second sensor signals indicate the hydration level of theuser.
 25. The non-transitory computer-readable medium of claim 21,wherein the multifunction surface comprises at least one electrode ofthe at least two electrodes.
 26. The non-transitory computer-readablemedium of claim 21, wherein a first electrode of the at least twoelectrodes is positioned at one end of the wearable device and a secondelectrode of the at least two electrodes is positioned at an oppositeend of the wearable device.
 27. The non-transitory computer-readablemedium of claim 21, wherein a first electrode of the at least twoelectrodes is positioned on a surface of the wearable device configuredto be worn against skin of the user and a second electrode of the atleast two electrodes is positioned on the multifunction surface.
 28. Thenon-transitory computer-readable medium of claim 21, further comprisingprocessor-executable instructions configured to cause a processor todetermine the bodily function measurement based on a pulse-transit-time(PTT) technique.
 29. The non-transitory computer-readable medium ofclaim 28, further comprising processor-executable instructionsconfigured to cause a processor to: determine a photoplethysmography(PPG) measurement based on the first sensor signals; determine anelectrocardiogram (ECG) measurement based on the second sensor signals;and determine a PTT using the PPT technique based on the PPG measurementand the ECG measurement, and wherein the bodily function measurement isbased on the PTT.
 30. The non-transitory computer-readable medium ofclaim 21, wherein the bodily function measurement comprises the stresslevel of the user, and further comprising processor-executableinstructions configured to cause a processor to output a notificationindicating the user should take a deep breath based on the stress level.